1. Field of the Invention
This invention relates to a photographing stand with a radiation image receiving portion for projecting radiation such as X-ray onto a subject lying down on the top plate of a lying stand such as a table or a bed, and photographing the radiation transmitted through the subject by a radiation image receiving portion disposed below or sideways of the top plate.
2. Related Background Art
A radiation photographing apparatus has heretofore been used in various fields such as the medical diagnosis of subjects and the non-destruction inspection of substances, and a so-called radiation photographing method using an intensifying screen and radiation photographic film brought into close contact with each other is adopted in the apparatus of this kind. In this apparatus, when radiation transmitted through an object enters the intensifying screen, a fluorescent material included in the intensifying screen absorbs the energy of the radiation and creates fluorescence, and the radiation photographic film is sensitized by this fluorescence and records a radiation image as a visible image.
In recent years, there has been devised an image recording-reproducing apparatus provided with a radiation detector comprising an accumulative fluorescent material. In this apparatus, when radiation transmitted through an object enters the accumulative fluorescent material, the accumulative fluorescent material accumulates part of radiation energy therein. When a light such as visible light is applied to the accumulative fluorescent material, the accumulative fluorescent material exhibits accelerated phosphorescence emission conforming to the energy accumulated therein. That is, the accumulative fluorescent material accumulates the radiation image information of the object therein, and scanning means scans the accumulative fluorescent material by excited light such as a laser beam, and reading means photoelectrically reads the accelerated phosphorescence emitted light, and an image signal read by the reading means is recorded or displayed as a visible image by a recording material such as a photosensitive material or display means such as a CRT.
Also, a radiation detector for directly digitally outputting radiation at real time has been proposed by the advance of the semiconductor process technique, and is described, for example, in Japanese Laid-Open Patent Application No. 8-116044. The radiation detector is constructed of a scintillator and a solid state photodetector stacked one upon the other, and the scintillator is adapted to convert radiation into visible light, and the solid state photodetector is adapted to photoelectrically convert the visible light. The solid state photodetector can be made by arranging solid state photodetector elements comprising transparent electrically conductive film and electrically conductive film in a matrix-like form on a substrate comprising quartz glass with amorphous semiconductor film interposed therebetween. Such a radiation detector is in the form of a flat panel having a thickness of several millimeters and therefore, a radiation image receiving portion using the radiation detector can be easily made thin and light in weight.
FIGS. 1A and 1B of the accompanying drawings show a prior-art photographing stand with a radiation image receiving portion having a radiation image receiving portion 1 containing a radiation detector therein and provided on a table 2, and the table 2 is of a construction in which a top plate 5 is supported on a supporting stand 3 through struts 4. The radiation image receiving portion 1 is supported on the upper portion of the supporting stand 3 through a rail stand 6 for movement in the axial direction of the top plate 5. A signal reading circuit, together with the radiation detector, is contained in the radiation image receiving portion 1, and the signal reading circuit is connected to an image processing portion, not shown, through a cable 7.
The photographing stand of this kind is provided with the radiation image receiving portion 1 using a radiation detector and therefore, the work of mounting and dismounting a cassette containing radiation photographic film or accumulative fluorescent material sheets therein, as in the prior art, or developing the radiation photographic film, or scanning a laser beam on the accumulative fluorescent material sheet becomes unnecessary, and the photographer can be liberated from a series of cumbersome work of this kind. That is, the photographer can move the radiation image receiving portion 1 to a desired position relative to a subject S lying down on the top plate 5 and photograph the desired region of the subject S, and can utilize a radiation image displayed by display means such as a CRT for diagnosis.
FIGS. 1C and 1D of the accompanying drawings show a prior-art photographing stand with a radiation image receiving portion using a cassette 1xe2x80x2 containing radiation photographic film on accumulative fluorescent material sheets therein together with a table 2xe2x80x2 which is comprised of a supporting stand 3, struts 4 and a top plate 5. When the side of a subject S is to be photographed by this photographing stand, it is necessary to vertically hold the cassette 1xe2x80x2 on the top plate 5 by a special supporting tool or the hand of the subject S, and when the side of the subject S is to be photographed on the bed of an ICU (intensive care unit), it is necessary for the photographer to vertically hold the cassette 1xe2x80x2.
Also, when the subject S lying down on the bed of the ICU has, for example, heart trouble, a great burden is applied to his or her heart when the subject S gets up. Therefore, the bed of the prior-art ICU is often provided with a tiltable movable top plate on at least one axial end portion of the top plate. When this bed is used, it is necessary to dispose the cassette 1xe2x80x2 behind the movable top plate after the latter is erected and moreover, it is necessary to photograph the lower half of the body of the subject S with the upper half of the body of the subject S erected.
Thus, to make the effectiveness of the tables 2, 2xe2x80x2 and the bed sufficiently displayed, it is necessary to hold the radiation image receiving portion 1 or the cassette 1xe2x80x2 in a posture which can be photographed from a plurality of different directions. However, to dispose the radiation image receiving portion 1 at a desired position, the following problems arise.
(a) The radiation image receiving portion 1 and the image processing portion are connected together by a cable 7 and moreover, the radiation image receiving portion 1 is heavier and larger than the cassette 1xe2x80x2 and therefore, it becomes necessary for the photographer to do the cumbersome work of taking out the radiation image receiving portion 1 from the underside of the top plate 5 and vertically standing it on the top plate 5 before photographing, and returning it from above the top plate 5 to below the top plate 5 after photographing.
(b) The radiation detector which is the main constituent of the radiation image receiving portion 1 is expensive and therefore, it becomes costly to individually prepare the radiation image receiving portion 1 in order to cope with different photographing, or to incorporate it into the bed of the ICU.
(c) The top plate of the bed of the ICU is not of a uniformly flat shape and therefore, to continuously move the radiation image receiving portion 1 along the top plate as by an operator""s hand, an excess space for movement becomes necessary in the under portion of the top plate.
(d) As a problem discrete from these problems, when a grid is used for the radiation image receiving portion 1 and side photographing is to be effected with the grid made stationary, moire attributable to the relation between the pixel pitch of the radiation detector and the arrangement pitch of the lead foil of the grid occurs on the radiation image.
(e) It is necessary to avoid to the utmost forcibly moving an emergency patient or a patient in a critical condition lying down on the bed of the ICU to the top plate 5 of the table 2 and therefore, to photograph the patient lying down on the bed of the ICU, it is also necessary to dispose the radiation image receiving portion 1 on the bed of the ICU.
It is an object of the present invention to solve some or all of the above-noted problems and to provide an inexpensive photographing stand with a radiation image receiving portion which can easily photograph from a plurality of different directions.
Other objects of the present invention will become apparent from the following detailed description of some embodiments of the invention.